Fig. 3.1: Symbol for piston compressor |Piston compressors draw in air by way of pistons moving up and down, compress it and then push it out. The processes control induction and pressure valves.|
By arranging several compression stages in series it is possible to generate various pressures, and differing quantities of air can be generated by using several cylinders.
Fig. 3.2: Op. diagram of plunger compressor |Plunger compressor |
On plunger compressors, the piston is connected directly to the crankshaft via the con-rod.
|Crosshead compressor |
The piston is powered by a piston rod and that by the crosshead.
Properties of piston compressors:
- Highly efficient
- High pressures
Fig. 3.3: Op. diagram of crosshead compressor
Fig. 3.4: V-type plunger compressor
Fig. 3.5: W-type plunger compressor
Fig. 3.6: Crosshead compressors
Horizontal, L-type, V-type, W-type
|The piston compressors are differentiated according to the arrangement of their cylinders:|
- Vertical cylinders.
No stress on the piston or piston ring through the weight of the piston.
Small base area.
- Horizontal cylinders.
Only as multi-cylinder compressor in Boxer construction. Low forces of gravity. This benefit is only noticeable when output is greater.
- V-, W- or L-type compressors.
Good mechanical balance.
Low space requirement.